At shafts of periodically operating machines, e.g., at a crankshaft of an internal combustion engine of a motor vehicle, during a rotary motion of the shaft interfering torsional vibrations occur, with their frequency changing with the rotation of the shaft. Particularly in the pulling operation, torsional vibrations are generated in the drive train of the motor vehicle by combustion processes of the internal combustion engine. In order to reduce these torsional vibrations, a centrifugal pendulum may be provided, which can compensate the torsional vibrations over a wider range of rotations of the internal combustion engine, ideally over its entire range of rotation. The centrifugal pendulums are based on the principle that due to centrifugal force, the pendulum weights tend to travel around a rotary axis at the largest possible distance when a rotary motion is initiated. The torsional vibrations in the shaft lead to an oscillating relative motion of the pendulum weights, with the centrifugal pendulum showing a natural frequency proportional to the rotation such that torsional vibrations can be compensated with frequencies, which are also equally proportional to the rotation of the shaft over a wide range of rotations.
A centrifugal pendulum comprises a plurality of pendulum weights, which are suspended via guide elements at a rotary pendulum weight carrier and that can perform a relative motion in reference to this pendulum weight carrier along predetermined guide paths, in order to here assume a variable distance from the axis of rotation of the pendulum weight carrier. As a consequence of the torsional vibrations in the drive train, the pendulum weights are excited to oscillate and/or vibrate, with their gravitational center permanently changing, temporarily off-set in reference to the torsional vibrations in the drive train, which causes a damping of the torsional vibrations by a mechanic feedback. An efficient damping can occur by an appropriate adjustment of the pendulum weights and their guide paths. In certain operating states of the centrifugal pendulum an impacting of the pendulum weights at the pendulum weight carrier can occur, an impacting of the faces of the pendulum weights neighboring in the circumferential direction, and/or an impacting of the guide elements in the respective longitudinal ends of the guide paths of the pendulum weight carrier and/or the pendulum weights, whereby malfunctions of the centrifugal pendulum and noise are generated, leading to a subjectively recognizable loss of driving comfort and noise.
The provision of the pendulum weights at a respective safety distance in reference to each other in the circumferential direction leads to an undesired reduction of the pendulum weights and/or the limitation of the escaping arc leads to a loss of efficiency of the centrifugal pendulum. Further, the use of rubber elements is hard to calculate with regards to tolerance under the impact of force with regards to aspects of thermal expansion and deformation. Here, reliability and lifespan of rubber elements are problematic in an oily environment. Further, rubber elements fail to prevent any impacting of pendulum weights adjacent in the circumferential direction, but they prevent it only between pendulum weights and the pendulum weight carrier. Furthermore, the terminals can only be used to a limited extent in centrifugal pendulums with a trapeze arrangement of the pendulum weights.
DE 198 31 160 A1 discloses a centrifugal pendulum for a shaft rotational about an axis with a trapeze arrangement of the pendulum weights. During operation of the centrifugal pendulum, a pendulum weight performs a purely translational motion in reference to the pendulum weight carrier of the centrifugal pendulum. This is achieved by a parallel bifilar suspension of the pendulum weights. In order for a small structural space to be well utilized, comparatively large pendulum weights are provided, with pendulum weights adjacent in the circumferential direction of the pendulum weight carrier being embodied rounded at the sides facing each other and contacting each other loosely independent from any deflection. By the facial, arc-shaped configuration of the pendulum weights, jamming pendulum weights can be essentially excluded, however here the noise development is even greater because the sides of the pendulum weights facing each other contact each other independent from any deflection of the pendulum weights, i.e., repeatedly impact each other when the operating conditions change.